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<div class="title">fld_lines.cpp</div>  </div>
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<p>An example using the FastLineDetector</p>
<div class="fragment"><div class="line"><span class="preprocessor">#include &lt;iostream&gt;</span></div><div class="line"></div><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../d1/d4f/imgproc_2include_2opencv2_2imgproc_8hpp.html">opencv2/imgproc.hpp</a>&quot;</span></div><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../df/d6c/ximgproc_8hpp.html">opencv2/ximgproc.hpp</a>&quot;</span></div><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../d6/d87/imgcodecs_8hpp.html">opencv2/imgcodecs.hpp</a>&quot;</span></div><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../d4/dd5/highgui_8hpp.html">opencv2/highgui.hpp</a>&quot;</span></div><div class="line"></div><div class="line"><span class="keyword">using namespace </span><a class="code" href="../../d8/dcc/namespacestd.html">std</a>;</div><div class="line"><span class="keyword">using namespace </span><a class="code" href="../../d2/d75/namespacecv.html">cv</a>;</div><div class="line"><span class="keyword">using namespace </span><a class="code" href="../../d9/d29/namespacecv_1_1ximgproc.html">cv::ximgproc</a>;</div><div class="line"></div><div class="line"><span class="keywordtype">int</span> main(<span class="keywordtype">int</span> argc, <span class="keywordtype">char</span>** argv)</div><div class="line">{</div><div class="line">    <span class="keywordtype">string</span> in;</div><div class="line">    <a name="_a0"></a><a class="code" href="../../d0/d2e/classcv_1_1CommandLineParser.html">CommandLineParser</a> parser(argc, argv, <span class="stringliteral">&quot;{@input|corridor.jpg|input image}{help h||show help message}&quot;</span>);</div><div class="line">    <span class="keywordflow">if</span> (parser.<a name="a1"></a><a class="code" href="../../d0/d2e/classcv_1_1CommandLineParser.html#a8c41cf242b2ad8c0472e3b57893ef200">has</a>(<span class="stringliteral">&quot;help&quot;</span>))</div><div class="line">    {</div><div class="line">        parser.<a name="a2"></a><a class="code" href="../../d0/d2e/classcv_1_1CommandLineParser.html#a84cda3794b765332bfe43bf8367222fb">printMessage</a>();</div><div class="line">        <span class="keywordflow">return</span> 0;</div><div class="line">    }</div><div class="line">    in = <a name="a3"></a><a class="code" href="../../d6/dba/group__core__utils__samples.html#ga3a33b00033b46c698ff6340d95569c13">samples::findFile</a>(parser.<a name="a4"></a><a class="code" href="../../d0/d2e/classcv_1_1CommandLineParser.html#a190215863579a6d244dccfd261ee0224">get</a>&lt;<span class="keywordtype">string</span>&gt;(<span class="stringliteral">&quot;@input&quot;</span>));</div><div class="line"></div><div class="line">    <a name="_a5"></a><a class="code" href="../../d3/d63/classcv_1_1Mat.html">Mat</a> image = <a name="a6"></a><a class="code" href="../../d4/da8/group__imgcodecs.html#ga288b8b3da0892bd651fce07b3bbd3a56">imread</a>(in, <a name="a7"></a><a class="code" href="../../d8/d6a/group__imgcodecs__flags.html#gga61d9b0126a3e57d9277ac48327799c80ae29981cfc153d3b0cef5c0daeedd2125">IMREAD_GRAYSCALE</a>);</div><div class="line"></div><div class="line">    <span class="keywordflow">if</span>( image.<a name="a8"></a><a class="code" href="../../d3/d63/classcv_1_1Mat.html#abbec3525a852e77998aba034813fded4">empty</a>() )</div><div class="line">    {</div><div class="line">        <span class="keywordflow">return</span> -1;</div><div class="line">    }</div><div class="line"></div><div class="line">    <span class="comment">// Create FLD detector</span></div><div class="line">    <span class="comment">// Param               Default value   Description</span></div><div class="line">    <span class="comment">// length_threshold    10            - Segments shorter than this will be discarded</span></div><div class="line">    <span class="comment">// distance_threshold  1.41421356    - A point placed from a hypothesis line</span></div><div class="line">    <span class="comment">//                                     segment farther than this will be</span></div><div class="line">    <span class="comment">//                                     regarded as an outlier</span></div><div class="line">    <span class="comment">// canny_th1           50            - First threshold for</span></div><div class="line">    <span class="comment">//                                     hysteresis procedure in Canny()</span></div><div class="line">    <span class="comment">// canny_th2           50            - Second threshold for</span></div><div class="line">    <span class="comment">//                                     hysteresis procedure in Canny()</span></div><div class="line">    <span class="comment">// canny_aperture_size 3            - Aperturesize for the sobel operator in Canny().</span></div><div class="line">    <span class="comment">//                                     If zero, Canny() is not applied and the input</span></div><div class="line">    <span class="comment">//                                     image is taken as an edge image.</span></div><div class="line">    <span class="comment">// do_merge            false         - If true, incremental merging of segments</span></div><div class="line">    <span class="comment">//                                     will be performed</span></div><div class="line">    <span class="keywordtype">int</span> length_threshold = 10;</div><div class="line">    <span class="keywordtype">float</span> distance_threshold = 1.41421356f;</div><div class="line">    <span class="keywordtype">double</span> canny_th1 = 50.0;</div><div class="line">    <span class="keywordtype">double</span> canny_th2 = 50.0;</div><div class="line">    <span class="keywordtype">int</span> canny_aperture_size = 3;</div><div class="line">    <span class="keywordtype">bool</span> do_merge = <span class="keyword">false</span>;</div><div class="line">    <a class="code" href="../../dc/d84/group__core__basic.html#ga6395ca871a678020c4a31fadf7e8cc63">Ptr&lt;FastLineDetector&gt;</a> fld = <a name="a9"></a><a class="code" href="../../df/ded/group__ximgproc__fast__line__detector.html#gaa9636e5033cd2939ec50810f2b2bd853">createFastLineDetector</a>(length_threshold,</div><div class="line">            distance_threshold, canny_th1, canny_th2, canny_aperture_size,</div><div class="line">            do_merge);</div><div class="line">    vector&lt;Vec4f&gt; lines;</div><div class="line"></div><div class="line">    <span class="comment">// Because of some CPU&#39;s power strategy, it seems that the first running of</span></div><div class="line">    <span class="comment">// an algorithm takes much longer. So here we run the algorithm 10 times</span></div><div class="line">    <span class="comment">// to see the algorithm&#39;s processing time with sufficiently warmed-up</span></div><div class="line">    <span class="comment">// CPU performance.</span></div><div class="line">    <span class="keywordflow">for</span> (<span class="keywordtype">int</span> run_count = 0; run_count &lt; 5; run_count++) {</div><div class="line">        <span class="keywordtype">double</span> freq = <a name="a10"></a><a class="code" href="../../db/de0/group__core__utils.html#ga705441a9ef01f47acdc55d87fbe5090c">getTickFrequency</a>();</div><div class="line">        lines.clear();</div><div class="line">        <a class="code" href="../../d1/d1b/group__core__hal__interface.html#ga7cde0074dfd288f2d70c0e035dacb28a">int64</a> start = <a name="a11"></a><a class="code" href="../../db/de0/group__core__utils.html#gae73f58000611a1af25dd36d496bf4487">getTickCount</a>();</div><div class="line">        <span class="comment">// Detect the lines with FLD</span></div><div class="line">        fld-&gt;detect(image, lines);</div><div class="line">        <span class="keywordtype">double</span> duration_ms = double(<a class="code" href="../../db/de0/group__core__utils.html#gae73f58000611a1af25dd36d496bf4487">getTickCount</a>() - start) * 1000 / freq;</div><div class="line">        cout &lt;&lt; <span class="stringliteral">&quot;Elapsed time for FLD &quot;</span> &lt;&lt; duration_ms &lt;&lt; <span class="stringliteral">&quot; ms.&quot;</span> &lt;&lt; endl;</div><div class="line">    }</div><div class="line"></div><div class="line">    <span class="comment">// Show found lines with FLD</span></div><div class="line">    <a class="code" href="../../d3/d63/classcv_1_1Mat.html">Mat</a> line_image_fld(image);</div><div class="line">    fld-&gt;drawSegments(line_image_fld, lines);</div><div class="line">    <a name="a12"></a><a class="code" href="../../d7/dfc/group__highgui.html#ga453d42fe4cb60e5723281a89973ee563">imshow</a>(<span class="stringliteral">&quot;FLD result&quot;</span>, line_image_fld);</div><div class="line"></div><div class="line">    <a name="a13"></a><a class="code" href="../../d7/dfc/group__highgui.html#ga5628525ad33f52eab17feebcfba38bd7">waitKey</a>(1);</div><div class="line"></div><div class="line">    <a class="code" href="../../dc/d84/group__core__basic.html#ga6395ca871a678020c4a31fadf7e8cc63">Ptr&lt;EdgeDrawing&gt;</a> ed = <a name="a14"></a><a class="code" href="../../d4/d8b/group__ximgproc__edge__drawing.html#gac06afd29523029534111a058c0711fd3">createEdgeDrawing</a>();</div><div class="line">    ed-&gt;params.EdgeDetectionOperator = EdgeDrawing::SOBEL;</div><div class="line">    ed-&gt;params.GradientThresholdValue = 38;</div><div class="line">    ed-&gt;params.AnchorThresholdValue = 8;</div><div class="line"></div><div class="line">    vector&lt;Vec6d&gt; ellipses;</div><div class="line"></div><div class="line">    <span class="keywordflow">for</span> (<span class="keywordtype">int</span> run_count = 0; run_count &lt; 5; run_count++) {</div><div class="line">        <span class="keywordtype">double</span> freq = <a class="code" href="../../db/de0/group__core__utils.html#ga705441a9ef01f47acdc55d87fbe5090c">getTickFrequency</a>();</div><div class="line">        lines.clear();</div><div class="line">        <a class="code" href="../../d1/d1b/group__core__hal__interface.html#ga7cde0074dfd288f2d70c0e035dacb28a">int64</a> start = <a class="code" href="../../db/de0/group__core__utils.html#gae73f58000611a1af25dd36d496bf4487">getTickCount</a>();</div><div class="line"></div><div class="line">        <span class="comment">// Detect edges</span></div><div class="line">        <span class="comment">//you should call this before detectLines() and detectEllipses()</span></div><div class="line">        ed-&gt;detectEdges(image);</div><div class="line"></div><div class="line">        <span class="comment">// Detect lines</span></div><div class="line">        ed-&gt;detectLines(lines);</div><div class="line">        <span class="keywordtype">double</span> duration_ms = double(<a class="code" href="../../db/de0/group__core__utils.html#gae73f58000611a1af25dd36d496bf4487">getTickCount</a>() - start) * 1000 / freq;</div><div class="line">        cout &lt;&lt; <span class="stringliteral">&quot;Elapsed time for EdgeDrawing detectLines &quot;</span> &lt;&lt; duration_ms &lt;&lt; <span class="stringliteral">&quot; ms.&quot;</span> &lt;&lt; endl;</div><div class="line"></div><div class="line">        start = <a class="code" href="../../db/de0/group__core__utils.html#gae73f58000611a1af25dd36d496bf4487">getTickCount</a>();</div><div class="line">        <span class="comment">// Detect circles and ellipses</span></div><div class="line">        ed-&gt;detectEllipses(ellipses);</div><div class="line">        duration_ms = double(<a class="code" href="../../db/de0/group__core__utils.html#gae73f58000611a1af25dd36d496bf4487">getTickCount</a>() - start) * 1000 / freq;</div><div class="line">        cout &lt;&lt; <span class="stringliteral">&quot;Elapsed time for EdgeDrawing detectEllipses &quot;</span> &lt;&lt; duration_ms &lt;&lt; <span class="stringliteral">&quot; ms.&quot;</span> &lt;&lt; endl;</div><div class="line">    }</div><div class="line"></div><div class="line">    <a class="code" href="../../d3/d63/classcv_1_1Mat.html">Mat</a> edge_image_ed = Mat::zeros(image.<a name="a15"></a><a class="code" href="../../d3/d63/classcv_1_1Mat.html#a146f8e8dda07d1365a575ab83d9828d1">size</a>(), <a name="a16"></a><a class="code" href="../../d1/d1b/group__core__hal__interface.html#ga88c4cd9de76f678f33928ef1e3f96047">CV_8UC3</a>);</div><div class="line">    vector&lt;vector&lt;Point&gt; &gt; segments = ed-&gt;getSegments();</div><div class="line"></div><div class="line">    <span class="keywordflow">for</span> (<span class="keywordtype">size_t</span> i = 0; i &lt; segments.size(); i++)</div><div class="line">    {</div><div class="line">        <span class="keyword">const</span> <a name="_a17"></a><a class="code" href="../../db/d4e/classcv_1_1Point__.html">Point</a>* pts = &amp;segments[i][0];</div><div class="line">        <span class="keywordtype">int</span> n = (int)segments[i].<a name="a18"></a><a class="code" href="../../df/d5b/namespacecv_1_1gapi_1_1streaming.html#a0a915e69f4cc8284293e40fc9ffbf157">size</a>();</div><div class="line">        <a name="a19"></a><a class="code" href="../../d6/d6e/group__imgproc__draw.html#ga1ea127ffbbb7e0bfc4fd6fd2eb64263c">polylines</a>(edge_image_ed, &amp;pts, &amp;n, 1, <span class="keyword">false</span>, <a name="a20"></a><a class="code" href="../../dc/d84/group__core__basic.html#ga599fe92e910c027be274233eccad7beb">Scalar</a>((rand() &amp; 255), (rand() &amp; 255), (rand() &amp; 255)), 1);</div><div class="line">    }</div><div class="line"></div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga453d42fe4cb60e5723281a89973ee563">imshow</a>(<span class="stringliteral">&quot;EdgeDrawing detected edges&quot;</span>, edge_image_ed);</div><div class="line"></div><div class="line">    <a class="code" href="../../d3/d63/classcv_1_1Mat.html">Mat</a> line_image_ed(image);</div><div class="line">    fld-&gt;drawSegments(line_image_ed, lines);</div><div class="line"></div><div class="line">    <span class="comment">// Draw circles and ellipses</span></div><div class="line">    <span class="keywordflow">for</span> (<span class="keywordtype">size_t</span> i = 0; i &lt; ellipses.size(); i++)</div><div class="line">    {</div><div class="line">        <a class="code" href="../../db/d4e/classcv_1_1Point__.html">Point</a> center((<span class="keywordtype">int</span>)ellipses[i][0], (<span class="keywordtype">int</span>)ellipses[i][1]);</div><div class="line">        <a name="_a21"></a><a class="code" href="../../d6/d50/classcv_1_1Size__.html">Size</a> axes((<span class="keywordtype">int</span>)ellipses[i][2] + (<span class="keywordtype">int</span>)ellipses[i][3], (<span class="keywordtype">int</span>)ellipses[i][2] + (<span class="keywordtype">int</span>)ellipses[i][4]);</div><div class="line">        <span class="keywordtype">double</span> angle(ellipses[i][5]);</div><div class="line">        <a name="_a22"></a><a class="code" href="../../d1/da0/classcv_1_1Scalar__.html">Scalar</a> color = ellipses[i][2] == 0 ? <a class="code" href="../../dc/d84/group__core__basic.html#ga599fe92e910c027be274233eccad7beb">Scalar</a>(255, 255, 0) : <a class="code" href="../../dc/d84/group__core__basic.html#ga599fe92e910c027be274233eccad7beb">Scalar</a>(0, 255, 0);</div><div class="line"></div><div class="line">        <a name="a23"></a><a class="code" href="../../d6/d6e/group__imgproc__draw.html#ga28b2267d35786f5f890ca167236cbc69">ellipse</a>(line_image_ed, center, axes, angle, 0, 360, color, 2, <a name="a24"></a><a class="code" href="../../d6/d6e/group__imgproc__draw.html#ggaf076ef45de481ac96e0ab3dc2c29a777a85fdabe5335c9e6656563dfd7c94fb4f">LINE_AA</a>);</div><div class="line">    }</div><div class="line"></div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga453d42fe4cb60e5723281a89973ee563">imshow</a>(<span class="stringliteral">&quot;EdgeDrawing result&quot;</span>, line_image_ed);</div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga5628525ad33f52eab17feebcfba38bd7">waitKey</a>();</div><div class="line">    <span class="keywordflow">return</span> 0;</div><div class="line">}</div></div><!-- fragment --> </div><!-- contents -->
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